In the lesson linked below, students will predict the number of solutions to a system of linear equations by using their thinking map and then solve system of linear equations by substitution. Students will discover that if the simplified solutions equivalent (i.e., 3 = 3), there are infinitely many solutions. Students will discover that when the equations are not equal (i.e., 4 ≠ 6), there is no solution to the system of linear equations.
Lesson guidelines: http://auhsdmath.pbworks.com/w/file/fetch/60768806/7_0Teach_Dir_Systems%282%29.pdf
Special cases Handout: http://auhsdmath.pbworks.com/w/file/fetch/60768808/7_1SpecialCases%282%29.pdf